Patent application title: BRAKE DISK

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Abstract:

A brake disk is described that has a friction ring and a disk chamber
connected to the friction ring via connecting links. Bores, into which
the connecting links are inserted, are formed in the circumference of the
friction ring. The connecting links are calibrated using a die before
being inserted into the bore. A calibration ball is introduced into the
bore with the aid of which the wall of the bore is calibrated when the
connecting link is inserted.

Claims:

1-10. (canceled)

11. A ventilated brake disk, comprising: a friction ring and a supporting
structure; and a plurality of connecting links connected to the
supporting structure being present on the circumference of the supporting
structure, the connecting links projecting into bores of the friction
ring, wherein the walls of the bores are calibrated.

12. The brake disk of claim 11, wherein the surfaces of the connecting
links are calibrated.

13. The brake disk of claim 11, wherein the connecting links are
supported in the bores in a sliding manner.

14. The brake disk of claim 11, wherein the bores are blind bores and the
calibration element is located between the bottom of the blind bore and
the connecting link.

15. The brake disk of claim 11, wherein the end of the connecting link
and the calibration element are configured to correspond to one another.

16. The brake disk of claim 11, wherein the end of the connecting link is
configured to be dome-shaped.

17. The brake disk of claim 11, wherein the calibration element is a
ball.

19. The brake disk of claim 11, wherein the disk chamber is made of a
light metal, in particular aluminum, the friction ring is made of cast
iron and the connecting links are made of stainless steel.

20. The brake disk of claim 11, wherein the connecting link is one of a
pin and a bolt.

Description:

FIELD OF THE INVENTION

[0001] The present invention relates to a brake disk, in particular a
ventilated brake disk, having a friction ring and a supporting structure,
in particular a disk chamber, connected to the friction ring via
connecting links.

BACKGROUND INFORMATION

[0002] A ventilated brake disk, which has a friction ring and a supporting
structure connected to the friction ring by connecting links, is
discussed in DE 43 32 951 A1. The connecting links are configured in
particular as pins, bolts, or the like, and are positioned over the
circumference of the supporting structure. The connecting links project
into recesses in the circumferential wall of the friction ring. In the
presence of high braking torques, there is the danger that the free
length of the connecting links, i.e., the distance between the supporting
structure and the friction ring, may, in the extreme case, cause the
connecting links to bend and become detached from their seat. In the case
of this and other brake disks in common use, the pins are introduced into
the bore using a so-called sliding fit. The surface of the pins is
polished and the bore wall is ground. According to the grinding or
polishing process used, machining traces running in a radial direction
are created, which means that they are formed at nearly a right angle to
the pin's direction of movement in the bore. The machining traces on the
surfaces may thus stick to one another and thus impede the movement of
the pin in the bore. Since the pin is made of stainless steel and the
brake disk is made of gray iron, these two components exhibit varying
expansions at the temperatures arising during operation. In the extreme
case, this may even cause the tolerance range provided for the sliding to
be exceeded, and the pins may become stuck in the bore. This would mean
that the sliding fit provided for and set to room temperature would
develop into an interference fit during operation. This prevention of the
pins from sliding in the bores may result in warps or cracks in the
friction ring. Furthermore, when the brake disk is subsequently cooled,
noises might be created by the radial machining traces which now separate
again. Furthermore, a plurality of machining steps is necessary during
manufacturing, so that the wall of the bore must be ground and the wall
of the pin polished in each machining step, and the pin must subsequently
be introduced into the bore as an additional manufacturing step. This
makes the manufacturing of these brake disks complex and expensive.

SUMMARY OF THE INVENTION

[0003] In contrast, the brake disk according to the present invention
having the characterizing features described herein has the advantage
that the necessary machining processes are reduced. When the pin is
inserted into the bore, a precision calibration ball is used to calibrate
the walls of the bore simultaneously. This not only smooths the surface
of the bore but also hardens the surface to a specific penetration depth.
Prior to this, the pin may be calibrated using a die. When the surface of
the bore or the surface of the pin is calibrated, no circular structures
are produced, but instead axial structures, i.e., structures running in
the direction of movement of the pin are produced at most. As a result,
the structures of the pins and the bores are no longer able to influence
one another at both room temperature and at operating temperature. This
makes it easily possible to set the tolerance range necessary for
error-free braking even at operating temperature due to the thermal
stresses. This means that both the tolerance range and the manufacturing
costs are reduced. If the faces of the pins are dome-shaped, the pin may
be used to guide the calibration ball through the bore with pressure. The
dome shape makes it possible to distribute the application pressure of
the pin over a larger area of the calibration ball, thus preventing the
end of the pin from being deformed by joining pressure or calibration
pressure that may occur. If the length of the bore is appropriately
configured, the calibration ball may also remain in the bore without
influencing the function of the brake disk in the case of a blind bore.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 shows a top view of a brake disk.

[0005] FIG. 2 shows a perspective representation, such as would result in
a partial section A/A through the brake disk according to FIG. 1.

DETAILED DESCRIPTION

[0006] In FIG. 1, a brake disk is denoted as 10, the brake disk being made
up of a disk chamber 11 and a friction ring 12. In a known manner, disk
chamber 11 is attached to a hub of a vehicle in a manner not shown here,
the screws for fastening protruding through bores 13 of disk chamber 11.
Disk chamber 11 is connected to friction ring 12 via a large number of
connecting links in the form of pins 16 or bolts, or the like, formed in
circumferential wall 15 of disk chamber 11. Friction ring 12 is made up
of two friction ring halves 12a and 12b which are connected to one
another by a large number of webs 17 distributed over the circumference
and running in particular in the radial direction, resulting in a
ventilated brake disk. Supporting webs 18 are formed in sections in the
area of the inner circumference of friction ring 12. These supporting
webs 18 have a continuous bore 19 for accommodating pins 16. However,
blind bores would also be conceivable. These bores 19 are shown in the
drawings in the central longitudinal axis of friction ring 12. However,
an offset of these bores 19 would also be possible.

[0007] In the area of bores 19, supporting webs 18 have projections 20
formed in the direction of disk chamber 11. Projections 20 also have
continuous bores 21 which are in alignment with bores 19. A small gap 22
is present between the face of projections 20 and the circumference of
disk chamber 11. Friction ring 12 is made of cast iron while disk chamber
11 is made of a light metal, in particular aluminum or magnesium. Pin 16
is made of stainless steel, in particular non-rusting stainless steel.
Pins 16 are calibrated using a die. Corresponding to the calibration, the
surface of the pin is compressed to a slight depth of penetration and is
thus also. hardened. Due to the movement taking place during calibration,
pin 16 has an elongated surface structure resulting from the calibration
only in its longitudinal direction, i.e., in its later direction of
movement in bore 19. When pin 16 is manufactured, spherical caps may be
pressed onto its end. As shown in FIG. 2, calibration ball 25 has a
slightly larger diameter than bore 21 and bore 19. This larger diameter
causes the wall of bore 21 and 19 to be compressed. After respective
calibration ball 25, pins 16 are inserted into bores 21 and 19 and are
introduced into bores 21 and 19 at a corresponding pressure, so that the
wall of bore 21 and 19 is calibrated as a result of calibration ball 25
being pushed ahead of pin 16.

[0008] If bore 19 is configured as a continuous bore and pin 16 is of
appropriate length, calibration ball 25 may be pushed out of bore 19
again at the end of the bore and removed if necessary. However, without
influencing the function of the brake disk, it would also be conceivable
for calibration ball 25 to remain in bore 19 in the case of a blind bore.
The face of pin 16 may be configured in various ways. It is particularly
advantageous if it is configured as a so-called "spherical cap" which
corresponds to the shape of calibration ball 25. As a result, the
application pressure of pin 16 onto calibration ball 25 is distributed
over a greater area, thus preventing the end of pin 16 facing calibration
ball 25 from being deformed. After the calibration process, pins 16
remain in bores 19, so that disk chamber 11 may subsequently be cast on.
In this connection, heads 16a of pins 16 are also cast into outer wall 15
of disk chamber 11. Projections 20 may also be used for accommodating
disk chamber 11 in the casting die. The casting is performed directly
onto the faces of projections 20 of friction ring 12.

[0009] Aforementioned gap 22 is produced when disk chamber 11 is cooled.
However, it should be configured to be as slight as possible. Friction
ring 12 is configured to be floating on disk chamber 11. To that end,
pins 16 must be situated in bores 19 with relatively slight play and
configured as above to have as low tolerance as possible, so that
friction ring 12 is able to move slightly on pins 16 both at room
temperature and at operating temperature. This tolerance range is
necessary since friction ring 12 is heated during the braking operation
and expands away from disk chamber 11 in the radial direction.

[0010] In FIG. 2, an overhang 30 has been formed on outer wall 15 of disk
chamber 11, the overhang encompassing projection 20 radially. Overhang 30
must be longer than gap 22; in particular, it must also entirely cover
the enlargement of the gap caused by the thermal expansion of friction
ring 12. This means that in any situation, overhang 30 should conceal gap
22 which may become enlarged; in particular it should entirely cover it.
Since, however, absolute imperviousness is not possible due to the slight
relative movement between overhang 30 and projection 20, a
temperature-resistant lubricant is situated in gap 22. On the one hand,
this ensures the sliding process of pin 16 in bore 19 and, on the other
hand, prevents corrosion caused by a de-icing agent that may penetrate
into gap 22. However, it would also be conceivable to design disk chamber
11 without overhang 30 without departing from the object of the exemplary
embodiments and/or exemplary methods of the present invention.